Geographic Distribution and Ecology of Triatoma dimidiata (Hemiptera: Reduviidae) in Colombia.

Triatoma dimidiata Latreille is the second most important vector of Chagas' disease in Colombia and is found in urban and periurban areas. From January 2007 to June 2008, we performed field work in 8 departments, 18 municipalities, and 44 rural villages, covering most of its known distribution and all of its ecological zones in the country. The goal was to determine the geographical distribution, the ecology, and house infestation indices of T. dimidiata over its range and hence the Chagas' disease transmission risk. In Colombia, T. dimidiata occupies a wide variety of ecosystems, from transformed ecosystems in the Andean biome with shrub and xerofitic vegetation to very dense forests in the humid tropical forests in the Sierra Nevada of Santa Marta. According to genetic and ecological criteria, at least two T. dimidiata forms of this species are present: populations from the northwest of the country (Caribbean plains) are restricted to palm tree habitats, and domestic involvement is limited to sporadic visits because of attraction by light; and populations of the east region (Andean mountains) presenting a complex distributional pattern including sylvatic, peridomestic, and domiciliated ecotopes, and occupying a great variety of life zones. The latter population is of epidemiological importance due to the demonstrated migration and genetical flow of individuals among the different habitats. Control, therefore, must take into account its diversity of habitats.

Geometric morphometrics for the taxonomy of 11 species of Anopheles (Nyssorhynchus) mosquitoes.

The subgenus Anopheles (Nyssorhynchus) (Diptera: Culicidae) includes the primary vectors of Plasmodium spp. in Colombia. Most adult females of this subgenus are difficult to identify in the field using the available keys. With the objective of further investigating the discriminatory power of modern morphometrics, both landmark-based and outline-based approaches were explored using the wing venation geometry of 11 Anopheles (Nyssorhynchus) species. Wing shape was able to separate the closest species of the subgenus. When the 11 species were analysed together, validated classification scores on average 5.3-8.6 times higher than those expected by chance were observed. These scores computed from the total sample of 11 species were not satisfactory for the recognition of Anopheles benarrochi B, Anopheles oswaldoi s.l. and Anopheles strodei. These sibling species were captured in sympatry. To improve the identification power of the morphometric tool, it was necessary to analyse these species separately from the remaining species. The best classification scores were obtained using a combination of 12 landmarks collected not only on the intersections of wing veins, but also on spots. An outline approach also gave excellent reclassification scores. Another pair of sibling species, collected in allopatry, Anopheles nuneztovari and Anopheles rangeli, also showed high classification scores.

Rhodnius barretti, a new species of Triatominae (Hemiptera: Reduviidae) from western Amazonia.

Rhodnius barretti, a new triatomine species, is described based on adult specimens collected in rainforest environments within the Napo ecoregion of western Amazonia (Colombia and Ecuador). R. barretti resembles Rhodnius robustus s.l., but mitochondrial cytochrome b gene sequences reveal that it is a strongly divergent member of the "robustus lineage", i.e., basal to the clade encompassing Rhodnius nasutus, Rhodnius neglectus, Rhodnius prolixus and five members of the R. robustus species complex. Morphometric analyses also reveal consistent divergence from R. robustus s.l., including head and, as previously shown, wing shape and the length ratios of some anatomical structures. R. barretti occurs, often at high densities, in Attalea butyracea and Oenocarpus bataua palms. It is strikingly aggressive and adults may invade houses flying from peridomestic palms. R. barretti must therefore be regarded as a potential Trypanosoma cruzi vector in the Napo ecoregion, where Chagas disease is endemic.

Characterization of Feeding Behavior and its Relationship With the Longevity of Wild and Peridomestic Triatoma dimidiata, Latreille 1811 (Hemiptera, Reduviidae) Under Laboratory Conditions.

Triatoma dimidiata (Latreille 1811) is considered the second most important vector of the Trypanosa cruzi etiological agent of Chagas disease in Colombia. It has a life cycle that involves a domiciled, peridomiciled, and wild distribution. The study of feeding behavior and its influence on the survival of sylvatic and peridomestic populations can help identify a possible differential risk in the transmission of Chagas disease to humans, mainly in northwestern and east-central Colombia. We characterize the main parameters of feeding behavior and their influence on the longevity and survival of two rat-fed populations of T. dimidiata from Colombia, one in the north-west (from palms in a tropical dry forest area) and the other in the center-east (peridomiciliated), under controlled environmental conditions. The palm population took considerably longer than the peridomestic population to complete its life cycle under experimental laboratory conditions, being both populations univoltine since they have only one life cycle per year. Statistically significant differences were evidenced using Box-Cox model between the survival rates of T. dimidiata populations when the parameters related to blood intake and behavior were incorporated, in contrast to the survival models in which the origin only was considered as a factor. Our results could be used to generate recommendations to guide prevention strategies in communities near sylvatic and peridomiciliated populations of T. dimidiata.

Environmental Determinants of the Distribution of Chagas Disease Vector Triatoma dimidiata in Colombia.

Triatoma dimidiata (Hemiptera: Reduviidae) is a secondary vector of Trypanosoma cruzi in Colombia and represents an important epidemiological risk mainly in the central and oriental regions of the country where it occupies sylvatic, peridomestic, and intradomestic ecotopes, and because of this complex distribution, its distribution and abundance could be conditioned by environmental factors. In this work, we explored the relationship between T. dimidiata distribution and environmental factors in the northwest, northeast, and central zones of Colombia and developed predictive models of infestation in the country. The associations between the presence ofT. dimidiata and environmental variables were studied using logistic regression models and ecological niche modeling for a sample of villages in Colombia. The analysis was based on the information collected in field about the presence ofT. dimidiata and the environmental data for each village extracted from remote sensing images. The presence of Triatoma dimidiata(Latreille, 1811) was found to be significantly associated with the maximum vegetation index, minimum land surface temperature (LST), and the digital elevation for the statistical model. Temperature seasonality, annual precipitation, and vegetation index were the variables that most influenced the ecological niche model ofT. dimidiata distribution. The logistic regression model showed a good fit and predicted suitable habitats in the Andean and Caribbean regions, which agrees with the known distribution of the species, but predicted suitable habitats in the Pacific and Orinoco regions proposing new areas of research. Improved models to predict suitable habitats forT. dimidiata hold promise for spatial targeting of integrated vector management.

Subcutaneous tissue involvement by T-cell lymphoma. A report of 2 cases.

BACKGROUND: T-cell lymphomas may involve the subcutaneous tissue as a manifestation of generalized disease. However, T-cell lymphomas rarely present with extensive involvement of the subcutaneous fat without other sites of disease. OBSERVATIONS: We describe 2 women who presented with fever and subcutaneous nodules or masses. In case 1, the nodules were generalized and did not respond to chemotherapy. The patient died 2 months after diagnosis. In case 2, the mass was large but localized and responded to chemotherapy. The tumor subsequently recurred in a cervical lymph node 9 months later, and the patient was being treated with chemotherapy 15 months after initial diagnosis. Histologically, biopsy specimens from both patients revealed malignant lymphoma involving the subcutaneous tissue. The dermis and epidermis were not involved. At low power the lesions resembled panniculitis, but high-power examination revealed cytologic atypia of the malignant lymphoid cells. Immunohistochemical studies revealed T-cell lineage. In case 2, the neoplastic cells also expressed the CD30 antigen, were positive for Epstein-Barr virus RNA, and carried the t(2;5) (p23;q35) chromosomal translocation. We interpreted case 1 as an example of subcutaneous panniculitic T-cell lymphoma. We believe that case 2 is best classified as anaplastic large cell lymphoma of T-cell lineage. CONCLUSIONS: A variety of T-cell lymphomas rarely present with only subcutaneous tissue involvement. Knowledge of this phenomenon and recognition of the cytologic atypia of the lymphoid cells will help to prevent misdiagnosis.

Practical guidelines for developing a hospital-based wound and ostomy clinic.

Multidisciplinary teams save time and money while improving quality of patient care. Hospital-based wound/ostomy clinics provide patients with holistic, one-stop, expert care with access to a variety of diagnostic and treatment modalities. The authors discuss how to assemble all the ingredients for a successful multidisciplinary hospital-based clinic, how to make it work, and how to measure its cost-effectiveness for patient, hospital, community and nation. The original model clinic established in Costa Rica using these methods was so successful at providing efficient, high quality, cost-effective care that it has been adopted in 17 different locations there, and similar clinics are being developed in other countries. This model is applicable to industrialized and developing countries. By focusing hospital resources on evidence-based wound/ostomy care, it has the potential to revolutionize wound and ostomy care around the world.

[Pollen of gramineae and its relation with allergic manifestations in Costa Rica]. / Los pólenes de gramíneas y su relación con manifestaciones alérgicas en Costa Rica.

Allergy to pollen is a significant health problem in Costa Rica. This volume both reviews and presents new data on the subject, for which there are no similar comprehensive studies in other areas of Latin America. A description of the sampling methods is presented, as well as an introduction to work presented throughout the volume. A hundred control subjects were compared with 480 patients with rhinitis, conjuntivitis, bronchial asthma and/or atopic dermatitis. Poaceae pollen ranks first in Type I allergic sensitivization, because (1) it produces abundant pollen, (2) occurs in a variety of climates and habitats and (3) its proteins are particularly allergenic. In 1986, about 0.33% of the country's population became new allergy patients, and the rate is increasing. The normal extraction methods were satisfactory and were applied to frozen pollen with a mean active life of about three years. Prich tests were done for a period of two years using only extract combinations by tribe. A second stage used species-specific extracts (1/10 W/V 50% glycerine).

[Type I hypersensitivity to graminea pollens by tribe, in allergic rhinitis patients]. / Hipersensibilidad tipo I a pólenes de gramíneas ordenados por tribu, en pacientes con rinitis alérgica.

Type I Hypersensitivity to pollens of the Poaceae Family (Gramineae) organized by subfamilies and tribes were studied in 404 Costa Rican patients with a clinical diagnosis of Allergic Rhinitis and 100 non atopic subjects. Skin prick tests (for each tribe) were done with pooled samples from the species which are most abundant in Costa Rica (1/10 W/V, 50% glycerinated). The tribes were: Paniceae, Andropogoneae, Poeae, Aveneae, Oryzoideae and Chloridoideae (Eragrostoideae); 53% of the patients were positive to at least one of the tribes against 2% of the non atopic subjects. The most frequent tribe was the Aveneae with a 37.4% of positivity; the lowest was Paniceae with an 24.8% positivity. The provinces with the highest positivities to graminean pollens were Alajuela and Guanacaste with more than 60% of the rhinitic patients positive for at least one test. When an individual is positive to one tribe, it does not mean that this patient is positive to other tribes of this large Family. It is necessary to include all the tribes of the Poaceae Family present in a country or region to properly analyze allergic hypersensitivity to this family.

[Type I hypersensitivity to pollen of the Poaceae family (Gramineae), by tribe, in atopic dermatitis patients]. / Hipersensibilidad tipo I a pólenes de la familia Poaceae (Gramineae) ordenados por tribu, en pacientes con dermatitis atópica.

Type I Hypersensitivity to Poaceae pollen was tested in 27 Costa Rican patients with a clinical diagnosis of Atopic Dermatitis (six were males). Skin prick tests were done with 1/10 W/V, 50% glycerinated, pollen extracts, organized by tribes. Most patients had several allergic problems. Sensitivity increased with the number of allergic diagnoses. Positivity ranged from 25% in patients with Atopic Dermatitis exclusively to 100% in those with three or four simultaneous allergic illnesses. Andropogoneae was highest with 37% while the lower positivity was in the Paniceae (22.2%).

[Type I hypersensitivity to gramineae pollen (by tribe), in allergic conjunctivitis patients]. / Hipersensibilidad tipo I a pólenes de gramíneas (por tribu), en pacientes con conjuntivitis alérgica.

A total of 84 Costa Rican patients with a clinical diagnosis of Allergic Conjuntivitis (with or without other allergic diagnosis) and 100 non atopic subjects were studied by prick tests for all of Poaceae Tribes present in Costa Rica. Positivity was recorded in 70% of the Allergic Conjunctivitis patients for at least one of the tribes (against 2% of controls). An increase in the number of analysed tribes correlated with a higher number of patients allergic to graminean pollens. Guanacaste Province had the highest positivity, and patients aged 11 to 20 years were the most sensitive. Aveneae had the highest positivity except in Alajuela Province, in which Paniceae was highest in positivity. Poaceae pollens are very important in allergic hypersensitivity among Allergic Conjunctivitis patients. Prick tests for all the tribes present in the country are required to fully detect positivity to this family.

[Type I hypersensitivity to gramineae pollen (by tribe), in bronchial asthma patients]. / Hipersensibilidad tipo I a pólenes de gramíneas (por tribu), en pacientes con asma bronquial.

A total of 260 Costa Rican patients (106 males) with clinical diagnosis of Bronchial Asthma and 100 non atopic subjects were studied with skin prick tests for all Poaceae tribes. Allergic Type I Hypersensitivity to these pollens among the Bronchial Asthma patients reached 51.2% positivity to at least one tribe (2% in controls). The positivity to each tribe was lower than positivity to at least one tribe. Up to 25.4% of positive patients could missed by not testing for all tribes present in the country. The pollen of the Oryzeae tribe (rice) showed the highest positivity among the Bronchial Asthma patients of Guanacaste Province. This province produces most of the country's grains. Type I Allergic Hypersensitivity to Poaceae Family pollens in Bronchial Asthma patients in Costa Rica was higher than expected.

[Type I hypersensitivity to gramineae pollen (by species) in allergic rhinitis patients]. / Hipersensibilidad tipo I a pólenes de gramíneas (por especie) en pacientes con rinitis alérgica.

A total of 184 Costa Rican Allergic Rhinitis patients with at least one positive skin prick test in a previous study were tested for reaction to Poaceae tribes and species compared with 100 non atopic subjects. Skin prick tests were applied for the most abundant species present in Costa Rica. Highest positivity rates among the Allergic Rhinitis patients were obtained with Anthoxatum odoratum (83.2%) (Tribe Aveneae), Panicum maximum (82.1%) (Paniceae), Panicum mole (78.3%) (Paniceae) and Holcus lanatus (77.7%) (Aveneae). The only species with a low percentage of positivity was Uniola pittieri. There was a high prevalence of positive prick tests to pollens of the Poaceae species used for food, including corn, sorghum, sugar cane and rice. All exceeded 60% of positive results in the patients (against 2% in controls). These cultivated species have a special pattern of flowering which can explain the known exhacerbation of allergic symptoms in patients with perennial allergic rhinitis.

[Correlation of allergy positivity for the tests of gramineas between tribes and species]. / Correlacion de positividades alérgicas para las pruebas de gramíneas entre tribus y especies.

In a sample of 190 Costa Rican allergic patients and 100 non atopic subjects there was a positive correlation of positivities in skin prick tests to individual Poaceae species and to the Tribe. The exceptions were Panicum maximun, Panicum molle, and Holcus lanatus, because they presented higher individual positivities. A table of correlations among tribes is included. Skin prick tests for Poaceae pollens should be organized by tribes to prevent a 25% of false negative cases.

Geometric morphometrics of nine field isolates of Aedes aegypti with different resistance levels to lambda-cyhalothrin and relative fitness of one artificially selected for resistance.

Aedes aegypti, a mosquito closely associated with humans, is the principal vector of dengue virus which currently infects about 400 million people worldwide. Because there is no way to prevent infection, public health policies focus on vector control; but insecticide-resistance threatens them. However, most insecticide-resistant mosquito populations exhibit fitness costs in absence of insecticides, although these costs vary. Research on components of fitness that vary with insecticide-resistance can help to develop policies for effective integrated management and control. We investigated the relationships in wing size, wing shape, and natural resistance levels to lambda-cyhalothrin of nine field isolates. Also we chose one of these isolates to select in lab for resistance to the insecticide. The main life-traits parameters were assessed to investigate the possible fitness cost and its association with wing size and shape. We found that wing shape, more than wing size, was strongly correlated with resistance levels to lambda-cyhalothrin in field isolates, but founder effects of culture in the laboratory seem to change wing shape (and also wing size) more easily than artificial selection for resistance to that insecticide. Moreover, significant fitness costs were observed in response to insecticide-resistance as proved by the diminished fecundity and survival of females in the selected line and the reversion to susceptibility in 20 generations of the non-selected line. As a practical consequence, we think, mosquito control programs could benefit from this knowledge in implementing efficient strategies to prevent the evolution of resistance. In particular, the knowledge of reversion to susceptibility is important because it can help in planning better strategies of insecticide use to keep useful the few insecticide-molecules currently available.

Description and characterization of the melanic morphotype of Rhodnius nasutus Stål, 1859 (Hemiptera: Reduviidae: Triatominae).

INTRODUCTION: For the first time we provide the description of the melanic (dark) morphotype of Rhodnius nasutus and determine the pattern of genetic inheritance for this characteristic. METHODS: Dark morph R. nasutus specimens were crossbred with standard (typically patterned) R. nasutus. RESULTS: We present the first occurrence of the melanic morphotype in the genus Rhodnius. The crossbreeding results demonstrate that the inheritance pattern of this characteristic follows Mendel's simple laws of segregation and an independent assortment of alleles. CONCLUSIONS: Phenotypic variation of R. nasutus reinforces the heterogeneity found in the Triatominae. Descriptions of new species in this subfamily require rigorous validation criteria.

Outline-based morphometrics, an overlooked method in arthropod studies?

Modern methods allow a geometric representation of forms, separating size and shape. In entomology, as well as in many other fields involving arthropod studies, shape variation has proved useful for species identification and population characterization. In medical entomology, it has been applied to very specific questions such as population structure, reinfestation of insecticide-treated areas and cryptic species recognition. For shape comparisons, great importance is given to the quality of landmarks in terms of comparability. Two conceptually and statistically separate approaches are: (i) landmark-based morphometrics, based on the relative position of a few anatomical "true" or "traditional" landmarks, and (ii) outline-based morphometrics, which captures the contour of forms through a sequence of close "pseudo-landmarks". Most of the studies on insects of medical, veterinary or economic importance make use of the landmark approach. The present survey makes a case for the outline method, here based on elliptic Fourier analysis. The collection of pseudo-landmarks may require the manual digitization of many points and, for this reason, might appear less attractive. It, however, has the ability to compare homologous organs or structures having no landmarks at all. This strength offers the possibility to study a wider range of anatomical structures and thus, a larger range of arthropods. We present a few examples highlighting its interest for separating close or cryptic species, or characterizing conspecific geographic populations, in a series of different vector organisms. In this simple application, i.e. the recognition of close or cryptic forms, the outline approach provided similar scores as those obtained by the landmark-based approach.

Genetic, cytogenetic and morphological trends in the evolution of the Rhodnius (Triatominae: Rhodniini) trans-Andean group.

The Rhodnius Pacific group is composed of three species: Rhodnius pallescens, R. colombiensis and R. ecuadoriensis, which are considered important vectors of trypanosomes (Trypanosoma cruzi and T. rangeli) infecting humans. This group is considered as a recent trans-Andean lineage derived from the widespread distributed sister taxa R. pictipes during the later uplift of northern Andes mountain range. The widest spread species R. pallescens may be a complex of two divergent lineages with different chromosomal attributes and a particular biogeographical distribution across Central America and Colombia with several southern populations in Colombia occupying the same sylvatic habitat as its sister species R. colombiensis. Although the taxonomy of Rhodnius Pacific group has been well studied, the unresolved phylogenetic and systematic issues are the target of this paper. Here we explore the molecular phylogeography of this species group analyzing two mitochondrial (ND4 and cyt b) and one nuclear (D2 region of ribosomal 28S gene) gene sequences. The molecular analyses suggest an early divergence of the species R. ecuadoriensis and R. colombiensis, followed by a recent expansion of R. pallescens lineages. The phylogenetic relationship between sympatric R. pallescens Colombian lineage and R. colombiensis was further explored using wing morphometry, DNA genome size measurements, and by analyzing chromosomal behavior of hybrids progeny obtained from experimental crosses. Our results suggest that the diversification of the two R. pallescens lineages was mainly influenced by biogeographical events such as (i) the emergence of the Panama Isthmus, while the origin and divergence of R. colombiensis was associated with (ii) the development of particular genetic and chromosomal features that act as isolation mechanisms from its sister species R. pallescens (Colombian lineage). These findings provide new insights into the evolution of the Rhodnius Pacific group and the underlying biological processes that occurred during its divergence.

Evaluación de la actividad antifúngica del extracto de Usnea laevis en hongos fitopatógenos / Evaluation of the antifungal activity of the lichenic extract of Usnea laevis in phytopathogenic fungi

Los líquenes son producto de una asociación simbiótica entre un hongo y alga y/o cianobacteria; esta simbiosis produce una serie de metabolitos secundarios o sustancias liquénicas únicas, las mismas que son aisladas a partir de sus extractos y que han presentado una marcada actividad antibiótica y antifúngica. Considerando que en el Ecuador no se tienen antecedentes acerca de este tipo de estudios, el objetivo planteado fue el evaluar la actividad antifúngica del extracto liquénico de Usnea laevis frente a hongos fitopatógenos. En el presente estudio las sustancias liquénicas almacenadas en el talo de Usnea laevis fueron extraídas con metanol y etanol. La actividad antifúngica in vitro de estos extractos fue probado frente a géneros de hongos fitopatógenos previamente aislados (Aspergillus, Penicillium y Rhizopus stolonifer); añadiéndolo al medio de cultivo Agar Papa Dextrosa (PDA) a una concentración de 0,5%; determinándose el porcentaje de inhibición. Los datos fueron analizados estadísticamente y se realizó la clasificación del extracto en base a su porcentaje de inhibición según la OILB. El extracto metanólico y etanólico de Usnea laevis mostró una mayor efectividad frente a Rhizopus stolonifer, inhibiendo más del 50% de su crecimiento, a diferencia de Penicillium y Aspergillus cuyo porcentaje de inhibición fue mucho menor y mostraron diferencias estadísticamente significativas. El extracto liquénico fue moderadamente tóxico para Rhizopus stolonifer, ligeramente tóxico para Aspergillus sp 1 y Penicillium sp e inocuo para Aspergillus sp 2.

A lichen is an organism product of a symbiotic association between a fungus and algae and / or cyanobacteria; this symbiosis produces many secondary metabolites or unique lichen substances, which are isolated from their extracts and show a marked antibiotic and antifungal activity. Considering there is no background on this type of studies in Ecuador, the aim of this study was to evaluate the antifungal in vitro activity of Usnea laevis extract on phytopathogenic fungi. The lichenic substances stored in the thallus of Usnea laevis were extracted with methanol and ethanol. The in vitro antifungal activity of these extracts was tested against phytopathogenic fungal genera previously isolated (Aspergillus, Penicillium and Rhizopus stolonifer) . They were adding to Potato Dextrose Agar (PDA) culture medium at a concentration of 0.5%, and the inhibition percentage was determined. Data were statistically analyzed and the extract was classified based on its inhibition percentage according to the OILB. Methanolic and ethanolic extracts of Usnea laevis showed greater effectiveness against Rhizopus stolonifer, inhibiting more than 50% of its growth, unlike Penicillium and Aspergillus, whose inhibition percentage was lower and showed significant differences. The liquid extract was also moderately toxic to Rhizopus stolonifer, slightly toxic to Aspergillus sp 1 and Penicillium sp and harmless to Aspergillus sp 2.

Eco-geographical differentiation among Colombian populations of the Chagas disease vector Triatoma dimidiata (Hemiptera: Reduviidae).

Triatoma dimidiata is currently the main vector of Chagas disease in Mexico, most Central American countries and several zones of Ecuador and Colombia. Although this species has been the subject of several recent phylogeographic studies, the relationship among different populations within the species remains unclear. To elucidate the population genetic structure of T. dimidiata in Colombia, we analyzed individuals from distinct geographical locations using the cytochrome c oxidase subunit 1 gene and 7 microsatellite loci. A clear genetic differentiation was observed among specimens from three Colombian eco-geographical regions: Inter Andean Valleys, Caribbean Plains and Sierra Nevada de Santa Marta mountain (SNSM). Additionally, evidence of genetic subdivision was found within the Caribbean Plains region as well as moderate gene flow between the populations from the Caribbean Plains and SNSM regions. The genetic differentiation found among Colombian populations correlates, albeit weakly, with an isolation-by-distance model (IBD). The genetic heterogeneity among Colombian populations correlates with the eco-epidemiological and morphological traits observed in this species across regions within the country. Such genetic and epidemiological diversity should be taken into consideration for the development of vector control strategies and entomological surveillance.